gfx/harfbuzz/src/hb-style.h

   1 /*
   2  * Copyright © 2019  Ebrahim Byagowi
   3  *
   4  *  This is part of HarfBuzz, a text shaping library.
   5  *
   6  * Permission is hereby granted, without written agreement and without
   7  * license or royalty fees, to use, copy, modify, and distribute this
   8  * software and its documentation for any purpose, provided that the
   9  * above copyright notice and the following two paragraphs appear in
  10  * all copies of this software.
  11  *
  12  * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
  13  * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
  14  * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
  15  * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
  16  * DAMAGE.
  17  *
  18  * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
  19  * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
  20  * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
  21  * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
  22  * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
  23  */
  24
  25 #if !defined(HB_H_IN) && !defined(HB_NO_SINGLE_HEADER_ERROR)
  26 #error "Include <hb.h> instead."
  27 #endif
  28
  29 #ifndef HB_STYLE_H
  30 #define HB_STYLE_H
  31
  32 #include "hb.h"
  33
  34 HB_BEGIN_DECLS
  35
  36 /**
  37  * hb_style_tag_t:
  38  * @HB_STYLE_TAG_ITALIC: Used to vary between non-italic and italic.
  39  * A value of 0 can be interpreted as "Roman" (non-italic); a value of 1 can
  40  * be interpreted as (fully) italic.
  41  * @HB_STYLE_TAG_OPTICAL_SIZE: Used to vary design to suit different text sizes.
  42  * Non-zero. Values can be interpreted as text size, in points.
  43  * @HB_STYLE_TAG_SLANT_ANGLE: Used to vary between upright and slanted text. Values
  44  * must be greater than -90 and less than +90. Values can be interpreted as
  45  * the angle, in counter-clockwise degrees, of oblique slant from whatever the
  46  * designer considers to be upright for that font design. Typical right-leaning
  47  * Italic fonts have a negative slant angle (typically around -12)
  48  * @HB_STYLE_TAG_SLANT_RATIO: same as @HB_STYLE_TAG_SLANT_ANGLE expression as ratio.
  49  * Typical right-leaning Italic fonts have a positive slant ratio (typically around 0.2)
  50  * @HB_STYLE_TAG_WIDTH: Used to vary width of text from narrower to wider.
  51  * Non-zero. Values can be interpreted as a percentage of whatever the font
  52  * designer considers “normal width” for that font design.
  53  * @HB_STYLE_TAG_WEIGHT: Used to vary stroke thicknesses or other design details
  54  * to give variation from lighter to blacker. Values can be interpreted in direct
  55  * comparison to values for usWeightClass in the OS/2 table,
  56  * or the CSS font-weight property.
  57  *
  58  * Defined by [OpenType Design-Variation Axis Tag Registry](https://docs.microsoft.com/en-us/typography/opentype/spec/dvaraxisreg).
  59  *
  60  * Since: 3.0.0
  61  **/
  62 typedef enum
  63 {
  64   HB_STYLE_TAG_ITALIC           = HB_TAG ('i','t','a','l'),
  65   HB_STYLE_TAG_OPTICAL_SIZE     = HB_TAG ('o','p','s','z'),
  66   HB_STYLE_TAG_SLANT_ANGLE      = HB_TAG ('s','l','n','t'),
  67   HB_STYLE_TAG_SLANT_RATIO      = HB_TAG ('S','l','n','t'),
  68   HB_STYLE_TAG_WIDTH            = HB_TAG ('w','d','t','h'),
  69   HB_STYLE_TAG_WEIGHT           = HB_TAG ('w','g','h','t'),
  70
  71   /*< private >*/
  72   _HB_STYLE_TAG_MAX_VALUE       = HB_TAG_MAX_SIGNED /*< skip >*/
  73 } hb_style_tag_t;
  74
  75
  76 HB_EXTERN float
  77 hb_style_get_value (hb_font_t *font, hb_style_tag_t style_tag);
  78
  79 HB_END_DECLS
  80
  81 #endif /* HB_STYLE_H */